The present invention relates to a hot water supply system and, more particularly, to a storage-type hot water supply system with a pulse combustor.
A pulse combustor has long been known as a combustor of high combustion efficiency. A pulse combustor comprises a pulse burner having a combustion chamber, and an elongate pipe, a so-called tail pipe, which communicates with the exhaust side of the combustion chamber. A pulse combustor is a combustor which operates similarly to a two-cycle engine and performs intermittent combustion at predetermined cycles. Exhaust gas is exhausted while it is pulsed within the tail pipe.
A pulse combustor as described above has the following advantages. Air and fuel gas are automatically fed to the combustion chamber due to a negative pressure generated within the combustion chamber of the pulse burner. Therefore, a blower or fan for supplying air is not required (except at the start of the operation of the combustor), and the blower can be of compact size. High load combustion can be performed, and a combustion chamber of small size can be used. Since the fuel gas is pulsed within the tail pipe as described above, a thermal transfer coefficient of about 3 to 5 times that of a conventional combustor may be obtained if such a tail pipe is used as a heat exchanger. The pulse combustor has other advantages. However, since the pulse combustor has high combustion efficiency as described above, it has a problem of creating excessive noise.
In a conventional hot water supply system which uses a pulse combustor as a heating source, a pulse burner of the pulse combustor is mounted at the upper portion of a storage tank. The tail pipe extends from the upper portion of the storage tank toward the lower portion thereof and then extends outside the tank from the lower portion thereof. This tail pipe is used as a heat exchanger. The exhaust gas which is passed through the tail pipe is cooled by a liquid within the storage tank and is condensed. Condensed water is thus produced within the tail pipe. In order to facilitate smooth discharge of the condensed water in the conventional hot water supply system of the type described above, the pulse burner of the pulse combustor is mounted on the upper portion of the storage tank and the tail pipe extends from the upper portion of the storage tank to the lower portion thereof. The conventional hot water supply system further has, for the purpose of reducing noise, a suction muffler which is arranged at the upper portion of the storage tank and which is connected to the combustion chamber, and an exhaust muffler which is arranged beneath the storage tank and which is connected to the exhaust side of the tail pipe. The storage tank, the suction and exhaust mufflers, and the pulse combustor are covered with a soundproofing material such as concrete.
In a hot water supply system of the type described above, the pulse burner and the suction muffler of the pulse combustor are arranged at the upper portion of the storage tank, while the exhaust muffler is arranged beneath the tank, providing a bulky overall system. Furthermore, since the pulse burner and the tail pipe of the pulse combustor (which are sources of noise) are present almost throughout the entire body of the system, soundproofing is difficult. Since the overall system is covered with a soundproofing material, the system becomes even more bulky and does not allow easy access for maintenance.